Floating covers for liquid storage tanks



Nov. 29, 1966 0. D. MARSHALL ETAL 3,288,322

FLOATING COVERS FDR LIQUID STORAGE TANKS Filed Jan. 25, 1965 2 SheetsSheet l INVENTOR; DAV) D05 mARsHAb-L .IRENIE MAKY NAM A xm a IQy- Q cum Nov. 29, 1966 D. 0. MARSHALL ETAL 3,

FLOATING COVERS FOR LIQUID STORAGE TANKS Filed Jan. 25, 1965 2 Sheets-Sheet DAVlD DrBiE MAHEMEE IRE/WE m/my' NAVLER United States Patent 3,288,322 FLOATING COVERS FOR LIQUID STORAGE TANKS David D. Marshall, Hale, and Irenie M. Nayler, Dudley,

England, assignors to Greengate & Irwell Rubber Company Limited, Salford, England, a body corporate of Great Britain, and Nayler (Petroseals) Limited, Dudley, England Filed Jan. 25, 1965, Ser. No. 427,674 Claims. (Cl. 220-26) This invention relates to improvements in floating covers for liquid storage tanks.

According to the invention a floating cover for a liquid storage tank is constructed from a plurality of sheets of fibre glass built up into units and secured together in situ to provide a buoyant cover capable of floating on the liquid in the tank, each sheet of fibre glass being supported on its underside with a buoyant frame of urethane foam to define therewith a unit, the said units being protected by a coating of a protective resin.

The invention will be described with reference to the accompanying drawings:

FIG. 1 is a vertical section through a tank showing the floating cover in position.

FIG. 2 is a plan of same with the top cover removed.

FIG. 3 is a side elevation to a larger scale of a portion of the floating cover.

FIG. 4 is a perspective view of a modified sheet and polyurethane log for affixing thereto.

A floating cover A for an enclosed cylindrical liquid storage tank B closed by a cover b is constructed from units each com-posed of a sheet a of fibre glass supported on a buoyancy frame a or log a of rigid urethane foam. The fibre glass sheets and the buoyancy frame or log are coated with antistatic polyester type resin or epoxy type resin or chemical modifications of these resins.

The units may be rectangular of up to 9 feet in length by say 21 inches in width with the frame a some 6 inches inside the edge of the sheet a, the sheet a and urethane frame a being united together by the resin coating in the mould or jig with the frame set back from the edge of the sheet.

The units are of a size to be introduced into the tank through a man hole or the like and assembled to form the cover in situ.

The edges of the sheets a of adjacent units are overlapped and secured together in rows, the end units in each row being cut to conform to the inner contour of the tank B.

In assembly the units are supported on aluminium or other light metal members d extending at right angles to the longer sides of the sheets, the light metal members being supported on legs d and secured together by a minimum of transverse tie rods. The units are secured together and to the metal mem'bers (FIG. 3).

Alternatively or in addition a separate metal framework al may be constructed to stand on legs d on the bottom of the tank B and assembly of the fibre glass sheets a takes place on top of this framework (FIG. 1).

In assembling the units together a sealing tape c coated with a rubber based adhesive is applied to the overlapping portions of the sheets a to provide a flexible joint to allow the cover to flex wit-h any ripples on the surface of the liquid in the tank B.

3,288,322 Patented Nov. 29, 1966 As shown in FIG. 4 the sheets a may be formed with ribs a moulded longitudinally of the longer sides to impart rigidity thereto and are mounted on logs a arranged intermediate the ribs.

A sealing ring D formed of flexible sponge foam enclosed in a skin engages the inner surface of the tank B, the sealing ring being carried by brackets D supported on the upper edge of the outer periphery of the cover.

The surface of the blanket may be provided with small drainage tubes a or sample hatches positioned at intervals across the whole area, to sample or drain off any product which gets on the upper surface of the blanket.

Holes or apertures d may be formed in the sheets a for the passage of dipping tube d anti-vibration wires d a weighted anti-static cable a one end of which is secured to the cover b or other instruments extending through wiping seals d carried on sleeves d affixed to a sheet a to prevent the escape of liquid or vapour from under the cover.

Liquid is introduced into the tank through an inlet pipe D A trap door may be fitted in the cover b to allow access to the upper surface of the floating cover.

What we claim is:

1. A floating cover for a liquid storage tank comprising a plurality of sheets of fibre glass, a rib moulded longitudinally of the longer sides of each sheet, a buoyant log of urethane foam secured to the underside of each sheet between the ribs to give buoyancy thereto, a rubber adhesive tape by which adjacent sheets are resiliently hinged together and a coating of protective resin over the sheet and tape to form a liquid proof seal.

2. A floating cover for a liquid storage tank having vertical side walls comprising a plurality of cover units each consisting essentially of a buoyant frame of plastic material carrying a sheet of fibre glass, said units being arranged with coextensive adjacent edges, means flexibly hinging adjacent units together at said edges, means providing a liquid proof layer of resin over each said unit which holds the frame and sheet in assembly, and means on the outer periphery of said floating cover sup-porting a flexible sealing ring engaging the side walls of the tank.

3. The floating cover defined in claim 2, wherein the sheets of said units are longitudinally formed with spaced ribs and wherein each said frame comprises a length of said plastic material underlying the sheet between said ribs.

4. The floating cover defined in claim 2, wherein said adjacent sheet edges overlap and are hinged together by a flexible seal strip extending along each overlap connection.

5. The floating cover defined in claim 2, wherein said flexible resin layer extends over said hinging means in the assembly.

References Cited by the Examiner UNITED STATES PATENTS 2,804,228 8/1957 Hartley 22026 2,873,042 2/1959 Fino 22026 2,914,212 11/1959 Fino 220-265 THERON E. CONDON, Primary Examiner.

JAMES B. MARBERT, Examiner. 

1. A FLOATING COVER FOR A LIQUID STORAGE TANK COMPRISING A PLURALITY OF SHEETS OF FIBRE GLASS, A RIB MOULDED LONGITUDINALLY OF THE LONGER SIDES OF EACH SHEET, A BUOYANT LOG OF URETHANE FOAM SECURED TO THE UNDERSIDE OF EACH SHEET BETWEEN THE RIBS TO GIVE BUOYANCY THERETO, A RUBBER ADHESIVE TAPE BY WHICH ADJACENT SHEETS ARE RESILIENTLY HINGED TOGETHER AND A COATING OF PROTECTIVE RESIN OVER THE SHEET AND TAPE TO FORM A LIQUID PROOF SEAL. 